I want to know how do I change my child's last name on his birth certificate or legally change it. I live in California the mother hased aggred for the change . She put her last name on the day of birth, certificate .so now we want to change it to my last name the child is 2 years old. I also want a estimate on how much is the cost for the legal servises.

If the mother is agreeable this should not be a problem. Go to your local family court and ask how to apply for a modification of the because. You should be able to do this for a minimal fee.

If you and the mother agree, and you merely want to have the child last name "changed" you can do that with a simple name change

It can be a more simple do it yourself, or with a para legal for a few hundred normally